Elastic Flat Bite Plate And Its Effect On Root Resorption Of The Anterior Teeth During Orthodontic Treatment Of Deep Overbite

Objective To develop a new elastic flat bite plate. To observe efficacy and root resorption amount of the anterior teeth by using this elastic flat bite plate compared with traditional rigid flat bite plate during orthodontic treatment of deep overbite, and comfort degree of patients in these two groups was also evaluated. The difference of bite force in these two groups was also investigated in order to explore the possible mechanism of elastic flat bite plate on root resorption.Methods Ethylene vinyl acetate (EVA) was selected to make elastic flat bite plate. Sixty-one cases with overbite were selected and randomly divided into observation group (21cases for the young subgroup,12 cases for the adult subgroup) and control group (17 cases for the young subgroup,11 cases for the adult subgroup). Both groups underwent orthodontic treatment, and we used elastic flat bite plate in the observation group and group rigid flat bite plate in the control group, respectively. Periapical films were taken before and after the process of stimulating root resorption, and tooth lengths and the root resorption of the anterior teeth was measured using these films. Comfort degree of patients in these two groups was questioned with self-made charts. Assessment of bite force was proceeded by T-Scan Ⅱ system.Results 1. A new elastic flat bite plate was developed, that was as effective as rigid flat bite plate to open occlusion (P> 0.05).2. Root resorption amount in the observation group was 0.79±0.29 mm, during which the root resorption amount for the young subgroup was 0.69±0.29 mm and adult subgroup was 0.96±0.19 mm, and they were respectively 1.03±0.25 mm,0.91±0.23 mm and 1.21±1.18 mm in the control group. Significant differences were found between the two groups (all P< 0.05). 3. Subjective degree of comfort in the observation group was significantly higher than the control group (P< 0.05).4. The bite force in the observation group was statistically smaller than the control group.Conclusions Comparing with the traditional rigid flat bite plate, the root resorption of the anterior teeth caused by elastic flat bite plate during orthodontic treatment of overbite is lighter, which was probably related to its smaller bite force applied to the anterior teeth. Elastic flat bite plate was an effective, safe and comfortable method in clinical orthodontic treatment of deep overbite, which deserve the clinical expansion application.